For many years now, there have been problems in the poultry-farming sector with regard to determining the fertility and sex of eggs before they are hatched.
Traditionally, sexing is done on a day-old chick by human intervention, chiefly via two techniques: feather sexing by observation of the feathers and vent sexing by observation of the vent.
Although these methods are efficient, their major drawback is that they come into operation too late in the production cycle. For example, in the case of laying hens, 21 days of incubation are needed to separate the females from the males (the latter are eliminated).
Determining the sex of embryos at an early stage of incubation would improve poultry farm production, with gains both in time and in financial profit.
A certain number of more or less invasive techniques have therefore been developed for determining and assessing the fertility and sex of a bird's not-hatched egg.
A first known technique is described in the U.S. Pat. No. 6,029,080, which proposes a method of determination by nuclear magnetic resonance. This technique is used to sort out the eggs into three categories: eggs containing male embryos, those containing female embryos and non-fertilized or “clear” eggs. The sorting is done by observation of the reproductive organs through the shell. More particularly, the observation can be done only after freezing the egg in order to minimize the movements of the embryo. One drawback of this technique is that the freezing of the egg causes disturbance in the future development of the embryo. Another drawback is that implementing such a technique is relatively costly. This acts as a brake on its industrial-scale development.
A second known technique is described in the patent application US2011/0144473, which describes the use of UV spectroscopy. This technique consists in sending out a wave in the ultraviolet domain so as to prompt auto-fluorescence in a region of the germinal disc (the blastodisc). To determine the sex of the embryo, a coefficient of decrease is computed and then compared with the database following the observation of the decrease of auto-fluorescence after the emission of the UV wave has been stopped. However, one drawback of this technique is that it requires access to the blastodisc by invasive removal.
A third known technique is based on infrared spectroscopy. This method which is also invasive consists of the introduction of a probe into the germinal disk region in order to characterize its constituent cells by infrared spectroscopy.
One major drawback of the second and third prior art techniques is that they are invasive: they require the introduction of instruments and the removal of cells from the germ. These operations are therefore not without risk for the future development of the embryo. Another drawback of these two techniques is the risk of contamination of the entire brood.
In order to overcome this major drawback, a fourth, non-invasive, prior art technique is described in the patent application US2013/0044210. It consists of a hyperspectral analysis (i.e. analysis from the mid-infrared to the near-UV) of an optical spectrum in reflection from the egg, in subtracting the spectral response of the shell and detecting the biological components of the egg. This technique can determine whether the egg is fertilized as of the second day and the sex of the embryo on the twelfth day. One major drawback of this technique is that it requires corrections to compensate for the shell (by subtracting its spectral response) and for environmental disturbances (light, humidity, etc.). To this end, each egg must be placed on a specific support maintaining a known distance between the radiation source, the detector and the egg. This technique is therefore difficult to carry out on an industrial scale.
Owing probably to the above-mentioned drawbacks, none of the prior art techniques cited above have truly led to industrial-scale development.